Stretch-activated container

ABSTRACT

A fluid-tight container adapted to contain a fluid, volatile solid, or absorbent for a fluid, in which at least a portion of the container includes a material which, when sufficiently stretched, develops sufficient porosity to allow passage of the fluid through the material. In some embodiments, the material may be a film. For example, the film may be a filled film. As another example, the film may be an elastic film, such as a hard-elastic film. In other embodiments, the material may be a laminate. Components of the laminate may be a film or a nonwoven web, in which case the film may be a filled film or an elastic film, such as a hard-elastic film. Desirably, the laminate will include a film and a nonwoven web. The fluid-tight container may include a fluid-absorbing solid, such as silica gel or activated carbon for absorbing moisture or odors. In such case, the movement of fluid through the material is into the container. Alternatively, the fluid-tight container may include a liquid. For example, the container may include a gel, cream, or lotion, in which case the movement of fluid through the material is from the container. Also provided is a method of dispensing a liquid which involves providing a fluid-tight container as described above, providing a liquid in the fluid-tight container, and stretching the container.

This application is a continuation of application Ser. No. 08/493,766entitled "STRETCH-ACTIVATED CONTAINER" and filed in the U.S. Patent andTrademark Office on Jun. 22, 1995, now U.S. Pat. No. 5,741,564. Theentirety of this application is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a container, such as a container for asolid or a fluid, e.g., a liquid or volatile material.

Numerous devices for dispensing a material are known. Such devices rangefrom a simple cloth to complex packages or containers for the controlledrelease of the material to be dispensed. Moreover, the material to bedispensed can be a solid, liquid, or gas.

Dispensing cloths include wet wipes and cloths impregnated with oil,lotion, or soap, all of which are concerned with skin care, particularlyfor infants. Dispensing cloths also have been employed for cleaning hardsurfaces. Devices functionally equivalent to dispensing cloths utilize amicroporous polymer for the dispensing of a wide variety of liquids,such as lubricants, surfactants, slip agents, moth repellents,pesticides, plasticizers, medicinals, fuel additives, polishing agents,stabilizers, insect and animal repellents, fragrances, flame retardants,antioxidants, odor-masking agents, antifogging agents and perfumes. Somecloths utilize microcapsules which may be ruptured to dispense amaterial.

More complex packages for dispensing a material are exemplified by adisposable swab having a rupturable container and a foam applicator incombination and a scrub sponge having a closed chamber which includes aclosed, puncturable chamber containing a liquid scrub agent and apuncture member. Another puncturable package is employed in a disposableliquid applicator for the cleaning and waxing of floors and othersurfaces. Other containers are utilized for dispensing a vapor from avolatile liquid.

A variety of laundry-related containers have been devised. These includecontainers for dispensing hydrogen peroxide into a clothes dryer for thebleaching of textiles, introducing detergent into a washer, andintroducing detergent into a washer and fabric softener into a dryer bymeans of a single container.

Notwithstanding the creativity applied in the past to the dispensing ofmaterials, there still is a need for improvements. For example, many ofthe known dispensers require either using all of the material containedtherein or storing the opened dispenser in another storage device, suchas an air-tight container. Moreover, the known dispensers generally donot provide for re-use at a later time; that is, the opening of thedispenser typically is not reversible.

SUMMARY OF THE INVENTION

The present invention addresses some of the difficulties and problemsdiscussed above by providing a fluid-tight container adapted to containa fluid, wherein at least a portion of the container comprises amaterial which, when sufficiently stretched, develops sufficientporosity to allow passage of the fluid through the material.

In some embodiments, the material may be a film. For example, the filmmay be a filled film. As another example, the film may be an elasticfilm, such as a hard-elastic film. In other embodiments, the materialmay be a laminate. Components of the laminate may be a film or anonwoven web, in which case the film may be a filled film or ahard-elastic film. Desirably, the laminate will include a film and anonwoven web. For example, the laminate may be a laminate of a film anda nonwoven web or a laminate of a first nonwoven web, a film, and asecond nonwoven web.

The fluid-tight container may include a fluid-absorbing solid, such assilica gel or activated carbon for absorbing moisture or odors. In suchcase, the movement of fluid through the material is into the container.

Alternatively, the fluid-tight container may include a liquid. Forexample, the container may include a gel, cream, lotion, or solution, inwhich case the movement of fluid through the material is from thecontainer.

The present invention also provides a method of dispensing a liquidwhich involves providing a fluid-tight container as described above,providing a liquid in the fluid-tight container, and stretching thecontainer. The liquid desirably will be a gel, cream, lotion, orsolution.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "fluid-tight container" means that thecontainer is impervious to gases or liquids, or to both gases andliquids. For example, the container may be pervious to gases, butimpervious to liquids, in which case the container is a liquid-tightcontainer. The term "fluid" is intended to include both gases andliquids.

The terms "porosity" and "connected porosity" are used herein to meansurface-connected pores, i.e, typically tortuous passageways or poreswhich extend from one surface of a material to the other surface.

The term "film" is used herein to mean a flat section of a thermoplasticpolymer whose thickness is very thin in relation to its width andlength. A film having a plurality of tortuous paths or passageways whichpermit the passage through the film of gases (i.e., porosity), includingwater vapor, but which is impervious to liquids present in the containeror to which the container may be exposed, is referred to herein as a"microporous film."

A "filled film" is a film which includes particulate matter which isinsoluble in the thermoplastic polymer from which the film was prepared.The particulate matter, or "filler," generally is present at levelsgreater than about 25 percent by weight, based on the weight of thepolymer, and often is present at levels greater than about 50 percent byweight. For example, the filler may be present at a level of from about25 to about 80 percent by weight. As another example, the filler may bepresent at a level of from about 60 to about 65 percent by weight, asdescribed in the examples. As is well known in the art, some filledfilms develop connected porosity upon being stretched. However, thedevelopment of such porosity is irreversible.

As used herein, the term "hard-elastic film" is meant to include a filmprepared from a polymer capable of exhibiting a high degree ofcrystallinity under conditions such that the film possesses not onlyincreased modulus and tenacity, but also unexpectedly largeextensibility and high elastic recovery from large extensions. Suchfilms (as well as fibers) also have been referred to in the art as "highmodulus-high recovery" and "springy" films (and fibers). See, forexample, S. L. Cannon et al., J. Polymer Sci.: Macromolecular Reviews,11, 209-275 (1976); and B. S. Sprague, J. Macromol. Sci.-Phys., B8(1-2),157-187 (1973).

The highly crystalline polymers develop row-nucleated structures ofstacked lamellar aggregates which can be further perfected by annealing.Hard-elastic films (and fibers) show abnormally high recovery from veryhigh strains, a negative temperature coefficient of retractive force,and high deformability with good recovery at liquid nitrogentemperature. More importantly, such films show a reversible reduction indensity on stretching with the generation of large, surface-connectedpores. Upon being stretched, hard-elastic films become porous and, as aconsequence, permeable to liquids. Unlike filled films, the porositydeveloped by hard-elastic films is reversed upon removal of the stress.

Examples of polymers from which hard-elastic films may be preparedinclude polyethylene, polypropylene-polyoxymethylene copolymers(Celcon), poly(3-methylbutene), poly(4-methylpentene), poly(ethylenesulfide), polypivalocatone, and, when specially annealed, nylon 6--6.

The term "fibrous material" is used broadly herein to mean any sheet orweb which is composed, at least in part, of fibers of any length. Thus,the fabric can be a woven or nonwoven sheet or web, all of which arereadily prepared by methods well known to those having ordinary skill inthe art. For example, nonwoven webs are prepared by such processes asmeltblowing, coforming, spunbonding, and carding. Moreover, the fabriccan consist of a single layer or multiple layers. When multiple layersare present, only one needs to be fibrous. Thus, a multilayered fabriccan include films, scrim, and other nonfibrous materials.

As used herein, the term "nonwoven web" means a web having a structureof individual fibers or threads which are interlaid, but not in anidentifiable manner as in a knitted fabric. Nonwoven webs are readilyprepared by known processes, such as meltblowing, coforming,spunbonding, air laying, wet laying, and the like.

The fluid-tight container of the present invention is adapted to containa fluid, volatile solid, or absorbent for a fluid. In general, at leasta portion of the container includes a material which, when sufficientlystretched, develops sufficient porosity to allow passage of the fluidthrough the material. For convenience, the term "stretchable material"is used herein to mean a material which, when sufficiently stretched,develops the required porosity.

The container may be of any size and shape. For example, the containermay be formed from two identical pieces of a stretchable material whichare overlaid and sealed around the edges to define a fluid-tight volumeor reservoir therebetween. Alternatively, one of the pieces may be astretchable material and the other piece may be a "stretchable layer;"the term is used herein to mean a layer which remains impervious tofluid after stretching.

The stretchable material may consist of a single layer or it may includetwo or more layers bonded together as a laminate. By way ofillustration, the stretchable material may be a film. For example, thefilm may be a filled film. As another example, the film may be ahard-elastic film. Further by way of illustration, the material may be alaminate. Components of the laminate may be a film or a nonwoven web, inwhich case the film may be a filled film or a hard-elastic film.Desirably, the laminate will include a film and a nonwoven web. Forexample, the laminate may be a laminate of a film and a nonwoven web ora laminate of a first nonwoven web, a film, and a second nonwoven web.

As already noted, the nonwoven web may be a nonwoven web prepared bysuch known processes as meltblowing, coforming, spunbonding, air laying,wet laying, and the like. As a practical matter, nonwoven webs preparedby meltblowing, coforming, and spunbonding are especially useful. By wayof illustration only, such processes are exemplified by the followingreferences, each of which is incorporated herein by reference:

(a) meltblowing references include, by way of example, U.S. Pat. No.3,016,599 to R. W. Perry, Jr., U.S. Pat. No. 3,704,198 to J. S.Prentice, U.S. Pat. No. 3,755,527 to J. P. Keller et al., U.S. Pat. No.3,849,241 to R. R. Butin et al., U.S. Pat. No. 3,978,185 to R. R. Butinet al., and U.S. Pat. No. 4,663,220 to T. J. Wisneski et al. See, also,V. A. Wente, "Superfine Thermoplastic Fibers", Industrial andEngineering Chemistry, Vol. 48, No. 8, pp. 1342-1346 (1956); V. A. Wenteet al., "Manufacture of Superfine Organic Fibers", Navy ResearchLaboratory, Washington, D.C., NRL Report 4364 (111437), dated May 25,1954, United States Department of Commerce, Office of TechnicalServices; and Robert R. Butin and Dwight T. Lohkamp, "Melt Blowing--AOne-Step Web Process for New Nonwoven Products", Journal of theTechnical Association of the Pulp and Paper Industry, Vol. 56, No.4, pp.74-77 (1973);

(b) coforming references include U.S. Pat. No. 4,100,324 to R. A.Anderson et al. and U.S. Pat. No. 4,118,531 to E. R. Hauser; and

(c) spunbonding references include, among others, U.S. Pat. No.3,341,394 to Kinney, U.S. Pat. No. 3,655,862 to Dorschner et al., U.S.Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,705,068 to Doboet al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. No.3,853,651 to Porte, U.S. Pat. No. 4,064,605 to Akiyama et al., U.S. Pat.No. 4,091,140 to Harmon, U.S. Pat. No. 4,100,319 to Schwartz, U.S. Pat.No. 4,340,563 to Appel and Morman, U.S. Pat. No. 4,405,297 to Appel andMorman, U.S. Pat. No. 4,434,204 to Hartman et al., U.S. Pat. No.4,627,811 to Greiser and Wagner, and U.S. Pat. No. 4,644,045 to Fowells.

In general, the polymer matrix of the stretchable material may be madefrom any thermoplastic polymer which possesses elastic properties.Examples of such thermoplastic polymers include, by way of example only,acrylonitrile-butadiene-styrene copolymers; cellophane; celluloseacetate; cellulose triacetate; fluorocarbon polymers, such asethylene-tetrafluoroethylene copolymers, fluorinated ethylene-propylenecopolymers, poly(chlorotrifluoroethylene), poly(tetrafluoroethylene),and poly(vinyl fluoride); ionomers; polyamides, such as nylon 6;polycarbonates; polyesters, such as poly(ethyleneterephthalate);polyimides; polyethylenes, such as low density polyethylenes, linear lowdensity polyethylenes, medium density polyethylenes, high densitypolyethylenes, and ultrahigh molecular weight polyethylenes;polypropylenes; polystyrenes; and rigid and plasticized poly(vinylchloride).

Depending upon the nature of the stretchable material, the fluid-tightcontainer of the present invention may be adapted for a single use orfor multiple uses. For example, when the stretchable material is afilled film, the development of pores in the film by stretching is notreversible. That is, once formed, the pores remain in the film after theremoval of the stress. Thus, a container made from a filled film is asingle-use container. However, the use of an elastic film, such as ahard-elastic film, as the stretchable material permits multiple usessince the removal of the stress closes the pores which were formed bystretching.

Most commonly, a fluid to be dispensed will be present in thefluid-tight container of the present invention. For example, the fluidmay be a liquid, such as a gel, cream, lotion, or solution. As examplesof suitable liquids, the following may be mentioned by way ofillustration only: hand and body lotions, cleansing creams, baby oil,disinfecting solutions, cleansing solutions, medicating gels, insectrepellent solutions, sunscreen lotions and oils, tanning lotions andoils, and the like.

A liquid need not be present in the container. Moreover, the movement ofa fluid through the stretchable material need not be from inside thecontainer to the outside. For example, a solid may be present in thecontainer. By way of illustration, the solid may be an absorbent such asactivated carbon or silica gel. In such case, the movement of fluidgenerally will be from outside the container to the inside, and thefluid typically will be a gas, such as water vapor or a malodorous gasor vapor. Alternatively, the solid present in the container may consistof a material which sublimes, such as naphthalene, in which casemolecules of naphthalene vapor will move from inside the container tothe outside.

Turning now to the method of the present invention, a liquid may bedispensed by providing a fluid-tight container as describedhereinbefore, providing a liquid in the fluid-tight container, andstretching the container. Upon stretching the container, pores areformed which allow a fluid to egress from the container. The fluidtypically will be a liquid.

In addition, a fluid may be captured within a container by providing afluid-tight container, wherein at least a portion of the containerincludes a material which, when sufficiently stretched, developssufficient porosity to allow passage of the fluid through the material.Provided in the fluid-tight container is a fluid-absorbing solid, suchas activated carbon or silica gel. Upon stretching the container, fluidis able to pass from outside the container, through the material whichhas been stretched, to inside the container where the fluid is absorbedby the fluid-absorbing material.

The present invention is further described by the examples which follow.Such examples, however, are not to be construed as limiting in any wayeither the spirit or the scope of the present invention. In theexamples, water containing a surfactant was employed as a model for anywater-based cleaning solution, home care, personal care, or skin careproduct; alcohol for any alcohol- or organic solvent-based product; andnaphthalene for any solid released by sublimation.

EXAMPLE 1

A nonwoven/film laminate was prepared by thermally point bondingessentially as described in, for example, U.S. Pat. No. 3,855,046 toHansen et al. and U.S. Pat. No. 4,493,868 to Meitner, a 0.5 ounce persquare yard or osy (about 17 grams per square meter or gsm)polypropylene spunbonded nonwoven web to a 0.5 osy (about 17 gsm)microporous film.

The spunbonded nonwoven web was produced essentially as described inU.S. Pat. No. 3,802,817 to Matsuki. The web was thermally point bondedbefore laminating, with a total bond area of about 15 percent.

The film formulation contained, on a total weight percent basis, 65percent English China Supercoat calcium carbonate (CaCO₃) with a 1micron average particle size and a 7 micron top cut. The calciumcarbonate was obtained from ECCA Calcium Products, Inc. in Sylacauga,Ala., a division of ECC International. The calcium carbonate was blendedwith 15 percent by weight of linear low density polyethylene made from ablend of Dowlex® 2517 linear low density polyethylene and Dowlex® 2532linear low density polyethylene blended in a weight ratio of 1:4 suchthat the melt index of the blend was 10 g/10 minutes. The melt index wasdetermined in accordance with ASTM Method D 1238-82, Standard TestMethod for Flow Rates of Thermoplastics by Extrusion Plastometer, usinga Model VE 4-78 Extrusion Plastometer (Tinius Olsen Testing MachineCompany, Willow Grove, Pa.) having an orifice diameter of 2.0955±0.0051mm at a temperature of 190° C. and a load of 2.16 kg. The Dowlex®polymers are available from Dow Chemical U.S.A., Midland, Mich. Theremaining 20 percent by weight of the formulation comprised HimontKSO51P polypropylene-based polymer from Himont, USA (Wilmington, Del.).The KSO51P polymer is an olefinic thermoplastic elastomer or TPOmultistep reactor product wherein an amorphous ethylene-propylene randomcopolymer is molecularly dispersed in a predominately semicrystallinehigh propylene monomer/low ethylene monomer continuous matrix. Theamorphous component acts as a tackifying or bonding agent as it beginsto soften at about 55° C.

The film formulations was blown into a film at a melt temperature of191° C. at a blow up ratio of approximately 1.7 to produce a film havingan unstretched basis weight of approximately 50 gsm. The filmsubsequently was stretched on a machine direction orientation (MDO) unitat a stretch ratio of 3× and at a temperature of 60° C. The resultantfilm was breathable (i.e., permeable to water vapor) and had a basisweight of approximately 14 gsm.

Two samples, each 3 inches by 3 inches (about 7.6 cm by 7.6 cm) wereplaced together, film-side to film-side, and thermally bonded or sealedalong three of the four edges by means of a Vertrod Thermal Impulse HeatSealer (Model 14P, Vertrod Corporation) to form a pouch open along oneedge. Three ml of isopropanol colored with ink was introduced into thepouch through the open edge which then was thermally sealed as describedabove. The procedure was repeated, except that the isopropanol solutionwas replaced with water colored with ink.

In each case, the liquid remained in the pouch without leakage throughthe sealed edges or the laminate. However, a slow weight loss over timewas observed as a result of the permeability of the laminate toisopropanol and water vapor.

Upon manually stretching either pouch in any direction, larger poreswere formed in the film layer of the laminate, thereby allowing liquidto flow through the laminate and wick or spread over the spunbondedlayer of the laminate in a controllable manner. That is, while theformation of larger pores by stretching was not reversible, the size ofthe pores and, consequently, the rate of flow of liquid through thelaminate, were readily controlled by the stretching force applied to thepouch. In other words, the rate of flow of liquid out of the pouch wasdirectly proportional to the stretching force applied. The liquid wastransferred to the skin by wiping.

EXAMPLE 2

Pouches were prepared as described in Example 1, except that each pouchwas made from an unstretched 45 gsm film having a thickness of 1.5 mils(about 38 micrometers). The film was prepared as described in Example 1from a composition comprising 60 percent by weight calcium carbonate, 14percent by weight of a random copolymer containing 5.5 percent by weightpolyethylene and 94.5 percent by weight polypropylene, and 26 percent byweight polypropylene, except, as already noted, the film was notstretched. Separate pouches were filled with isopropanol, naphthalene,and water, respectively. The pouches were maintained at ambienttemperature (about 20°-25° C.) in a constant air-flow fume hood andweight loss followed as a function of time. After one week, weight lossin each case was less than one percent. When the pouches were stretched,the film immediately became opaque, demonstrating the creation of poresin the film. Liquids contained in the pouches passed freely through thefilm; as the liquids passed through the film, the film again becametransparent as liquid filled the pores and reduced light scattering.

EXAMPLE 3

The procedure of Example 2 was repeated, except that the pouches wereprepared from a 1.5-mil (about 38-micrometer) thick filled film preparedas described in Example 2 from a composition comprising 63 percent byweight calcium carbonate, 19 percent by weight of the Dowlex® blenddescribed in Example 1, 13 percent by weight of the randomethylene-propylene copolymer employed in Example 2, and 5 percent byweight of low density polyethylene. No weight loss was observed when thepouches were stored at ambient temperature for 24 hours. When stretched,the pouches released liquids through the pores created by stretching.

While the specification has been described in detail with respect tospecific embodiments thereof, it will be appreciated that those skilledin the art, upon attaining an understanding of the foregoing, mayreadily conceive of alterations to, variations of, and equivalents tothese embodiments. Accordingly, the scope of the present inventionshould be assessed as that of the appended claims and any equivalentsthereto.

By way of illustration, a pouch may be made as described in Example 1from a laminate comprising, e.g., a 0.5 osy (about 17 gsm) polyethylenemetallocene nonwoven web thermally bonded to a 0.8 osy (about 27 gsm)calcium carbonate-filled film. The pouch may be filled with, forexample, a sunscreen lotion. When stretched, the film component of thelaminate develops sufficient porosity to allow the lotion to move to andbe distributed in the nonwoven web layer, thereby permitting thecontrolled application of lotion to skin. Less force is needed duringstretching because of the higher elongation of the metallocene nonwovenweb.

As a further illustration, a hard-elastic film prepared as described inU.S. Pat. No. 3,801,404 to Druin et al. or U.S. Pat. No. 5,238,760 toTakahashi et al. may be laminated to a polyethylene nonwoven web. Apouch containing, for example, mosquito repellent in an ethanol-basedsolution, may be made by bonding the edges with an adhesive or thermallyas described in Example 1. The pouch may be activated by stretchingwhich creates porosity in the film, thereby allowing some of thesolution to wick out to the nonwoven web. As soon as the stretchingforce is released, the pores created by the stretching process close,allowing re-use of the pouch until the supply of repellent is depleted.

Other modifications will be apparent to those having ordinary skill inthe art.

What is claimed is:
 1. A method of dispensing a liquid whichcomprises:providing a fluid-tight container adapted to contain a liquid,wherein at least a portion of the container comprises a material whichis initially in an unstretched condition so that the material isimpervious to liquids or both gases and liquids, said material beingconstructed of a film that, when stretched b manual forces external tosaid material, forms a plurality of surface-connected Pores to allowliquids and gases to penetrate said material so that liquids and gaseswill pass into or out of said container at a controlled rate dependingon the amount of external stretching force applied to said material;providing a liquid in the fluid-tight container; and stretching thecontainer.
 2. The method of claim 1, in which the material comprises afilm.
 3. The method of claim 2, in which the film is a filled film. 4.The method of claim 2, in which the film is a hard-elastic film.
 5. Themethod of claim 1, in which the material comprises a laminate of a filmand a fibrous material.
 6. The method of claim 5, in which the materialis a laminate of a film and a nonwoven web.
 7. The method of claim 5, inwhich the material is a laminate of a first nonwoven web, a film, and asecond nonwoven web.
 8. The method of claim 5, in which the film is afilled film.
 9. The method of claim 5, in which the film is ahard-elastic film.
 10. The method of claim 1, in which the liquid isselected from the group consisting of a gel, cream, and lotion.
 11. Amethod of capturing a fluid within a container which comprises:providinga fluid-tight container, wherein at least a portion of the containercomprises a material which is initially in an unstretched condition sothat the material is impervious to liquids or both gases and liquids,said material being constructed of a film that, when stretched by manualforces external to said material, forms a plurality of surface-connectedpores to allow liquids and gases to penetrate said material so thatliquids and gases will pass into or out of said container at acontrolled rate depending on the amount of external stretching forceapplied to said material; providing a fluid-absorbing solid in thefluid-tight container; and stretching the container.
 12. The method ofclaim 11, in which the material comprises a film.
 13. The method ofclaim 12, in which the film is a filled film.
 14. The method of claim12, in which the film is a hard-elastic film.
 15. The method of claim11, in which the material comprises a laminate of a film and a fibrousmaterial.
 16. The method of claim 15, in which the material is alaminate of a film and a nonwoven web.
 17. The method of claim 15, inwhich the material is a laminate of a first nonwoven web, a film, and asecond nonwoven web.
 18. The method of claim 15, in which the film is afilled film.
 19. The method of claim 15, in which the film is ahard-elastic film.